Effects of granulation-tissue extracts on collagen synthesis

The effect of granulation-tissue extract on the synthesis of collagen in embryonic-chick tendon cells was found to depend on (i) the developmental phase of the granulation tissue, (ii) the concentration of the extract and (iii) the presence of diffusible components in it. The suppressing effect was maximal with concentrated extracts from 2--3-week granulation tissue (where the collagen synthesis is also maximal). The suppressing factor could be enriched by gel filtration chromatography. Cultured human synovial cells were affected like the embryonic-chick cells. When the sponge implant was imbibed with granulation-tissue extract in advance, the developing granuloma contained less collagen than the control. The stimulating effects with dilute extracts from granulation tissue were due to diffusible components. Blood serum and rheumatoid synovial fluid samples also stimulated collagen synthesis in granulation-tissue slices, less after dialysis.